1812 North Moore
The $117 million 1812 North Moore project is a 390-foot, LEED Platinum designed new office tower that is be the tallest green building in metropolitan Washington, D.C. The 35-story, 580,000 square-foot building includes column-free, trophy-class office space and offers unparalleled 360-degree views of the Potomac River, the Washington monuments, and the Georgetown neighborhood.
Each floor of 1812 North Moore features 580 linear feet of high performance unitized curtain wall, maximizing direct lines of sight to Washington’s monumental core and the Potomac River. The tower is accented with a two-story, aluminum-clad steel pyramid at the top. Together with state-of-the-art security detail and 11,000 square feet of retail, 1812 North Moore also features five levels of underground parking and four levels of above-grade parking for a total of 480 parking spaces.
On the outside, the property is a skyline-altering, glass-curtain-wall-clad symbol of Arlington County’s premier office market. Inside, the 35-story structure features luxe elements such as a limestone-lined lobby, a feature wall made of Calacatta Borghini Italian marble, and nine-foot-tall ceilings. Post-tensioned beam construction with reinforced slabs was used to achieve an almost column-free interior layout that will provide future tenants with flexibility and, of course, more space.
The pyramid on top of the office building at 1812 North Moore Street is more than the project's signature feature – it was also the most challenging to fabricate and install. The team overcame significant technical and logistical obstacles in delivering 1812 North Moore's hallmark feature.
The pyramid's tolerances were so tight that the geometry required the team to use three-dimensional modeling and full-size connection jibs to maintain orientation. The pyramid structure had to be precise enough to accommodate glass panels from another subcontractor. Adding to the complexity, not only is the pyramid asymmetrical, but the pyramid legs, themselves, are asymmetrical pyramids.
Logistically, site access had to be carefully coordinated; the pyramid segments would not fit under any local bridges, the project had virtually no staging area and flight patterns to the nearby Ronald Reagan National airport had to be altered to accommodate the required night-time installation.
After years of design and coordination, pyramid construction began in late 2012 and was completed in March 2013.
The specialty metals and structural steel subcontractor used 3-D laser tube cutters to ensure the pipes fit properly at the gussets, which were oriented differently at each end of the pipes. They made full size connection jigs to ensure that the mirror image pyramid legs would be dimensionally identical. Once the four pyramid legs were constructed, each was cut in half for shipping. The subcontractor also designed a splice to connect the elements which were meeting at different angles, which proved to be a very difficult task.
Special road permits from several jurisdictions were required to transport the individual components to the assembly point in Arlington. Given the fact that the materials were 60’ long, 28’ wide and over 13’ high, selecting roadways that were wide enough to accommodate the load was a challenge. Each flatbed truck required a police escort while traversing their respective areas, and all transport took place overnight.
On top of the 35th floor, the specialty metals and structural steel subcontractor constructed a shoring tower to hold the compression ring and designed and installed a hydraulic jacking apparatus in opposing corners. This jacking apparatus allowed each leg to be supported without loading the compression ring. The specialty metals and structural steel subcontractor designed the base plates to allow the asymmetrical shape to rotate so the jacks would be able to raise and lower the structure. The components were lifted from the truck using a boom truck and custom rigged so they would not cause an uneven load as they were flipped over for hooking to the tower crane. The tower crane was used to fasten the bottom half of the legs in place on the 34th floor and rest the top against the hydraulic jacks. After the top half of each leg was set, the completed leg was lowered into the compression ring for fitment of the pins.
To complicate matters, the glass under the pyramid had to be complete prior to setting the pyramid—our guys did this work, and the full penetration welds on each leg, over the glass. No glass was damaged.
1812 North Moore’s support of excavation was a challenge to construct and required great craftsmanship due to its location in Northern Virginia’s dense, urban Rosslyn neighborhood. The site was constrained by the Rosslyn Metro Station to the south, a Dominion Virginia Power (DVP) Power Substation building to the north, existing underground utilities throughout the site, and high traffic roadways on the east and west, which came right to the edge of the support of excavation system.
Along the east and west sides of the site, the shoring system consisted of soldier beams and lagging, which extended to the rock. The shoring system then transitioned into shotcrete and rock bolts once rock was encountered. This shoring system required high quality craftsmanship to install due to the many challenges that were imposed by the site. The first of these challenges was the installation of the soldier beams along the edge of the high traffic roadways. This was compounded by managing the partially demolished 11-story brick and concrete building that needed to be removed as the excavation progressed. In order to install the soldier beams, a great amount of coordination was required.
The transition between the soil and rock support of excavation required great skill and workmanship as vertical bars and toe ties had to be installed at the toe of the soldier beams/bottom of the existing wall where the ground transitioned from soil to rock. Significant care and attention had to be employed to the sequencing and installation these supports to avoid settling the shoring system.
Along the north and south sides, the existing foundation wall had to be utilized due to the very limited space and proximity of the existing Metro and DVP buildings. The existing walls were reinforced and supported using a system of vertical steel strongbacks and tieback bracing.
Installation of the tieback bracing system required skilled craftsmanship, as it had to be coordinated with the demolition and removal of the existing building and to avoid the many underground utilities. Due to the close proximity of the DVP Substation, there were many high power 69kV oil cooled lines within the influence of the sheeting and shoring system. In order to miss these lines — which came as close as 5 feet from the tiebacks — the Clark Foundations team held numerous field meetings with the various affected utility companies and test pits had taken place and performed. Along the south side of the jobs, the tiebacks had to miss the existing Metro Station’s foundation caissons. Many hours were spent surveying and accurately laying out the existing caisson location in order to miss them.
1812 North Moore is one of the largest LEED Platinum office buildings in the country. The building has been certified LEED Gold for Neighborhood Development and is earned LEED Platinum for Core & Shell. All systems are controlled through digital electronic building management systems. This web-based programmable system allows for remote operation and optimizes the HVAC systems.
The high-efficiency series-counterflow low temperature chilled water HVAC system is unlike traditional self-contained packaged HVAC systems. Compared to the conventional HVAC system, the high-efficiency chilled water system consumes 31% less energy.